Howdy! New here but needin some help. I got a 1984 chevy c20,3/4 ton custom. Since I got my truck I’ve been rebuilding the rear axle and from the beginning noticed this arm that was bolted from the frame to the differential housing. Didn’t pay attention much till today when I was redoing the brake lines. I followed my brake lines up and found that they passed through the arm thing. I have no idea what this is. After running my brake lines, they are now in the way of attaching the arm back. I was just going to remove it, but now that I see the brake lines run through this arm thing I wanted to check what it was before removing it and splicing the brake line. Y’all have any clue? And can I remove it or is it needed for the brake system? Thanks in advance, best regards

brake line full route

view from the opposite side

view from the opposite side, how the brake lines route

 

If I remember correctly it's a rear brake pressure regulator valve. Used for rear brake antilock. As the rear of the truck goes up it limits hydraulic pressure to the rear brakes to keep the brakes from locking up. If removed you might have an issue with the rear brakes skidding. You might have to do some research, but I thought if you remove it you should install a 3 stage proportioning valve.

 

Ahhh okay okay that makes sense now. I've been researching a bit and most people just take them off. I'm kind of on a real tight budget and dont want to have to mess with splicing it. I removed the arm from the valve but now I do not know what position to put it back on for the valve to function as it should. I may just remove the arm and set the valve by hand and just leave it for now, frustrates me my new brake lines don't line up with the brake line tee mount on the load sensor arm anyway. Is there a way to tell what position the valve is in?

 

The technical term is height sensing proportioning valve.

As the weight in the bed of the truck changes, the arm adjusts the valve to allow more or less hydraulic pressure/flow to the rear brakes to compensate for the load. The rear brakes provide more stopping power when the truck is loaded to prevent the front brakes from getting too hot.

The more weight in the bed, the more pressure/flow to the rear brakes; and vice versa.

And as dpieroni3 pointed out, it also prevents the rear brakes from locking up when the truck is unloaded.

If you’re not going to be using the truck for towing or hauling, you can rig the valve. Reattach the arm and index the position on the valve with the truck at normal ride height, then remove the arm and use whatever means you have to secure the valve in place. Heavy duty zip ties should do it, but if you want to be able to “fine tune” the valve for braking, you’ll probably need to fabricate your own means of adjustment to lock the valve in place once it’s set.